Our invention relates to a method for lining a pipe laid in the ground, advantageously a waste water conduit made of concrete, asbestos cement or stoneware. It also relates to the sanitized conduit produced by this method.
A method for lining a pipe laid in the ground, especially a sewer conduit made from concrete, asbestos cement or stoneware, uses a lining tube having at least one layer made of a fiber fleece, whose fiber fleece layer is soaked with a hardenable plastic resin. The lining tube is introduced into the pipe, is pressed with a pressurizing medium on the inner surfaces of the pipe to be converted into a sanitary duct or conduit and the plastic resin is hardened.
A method of this type is described in German Patent 22 40 153, in which the lining tube is provided on the outer side with a fluid impermeable layer. Because of this impermeable layer one should be able to omit a previously required cleaning of the pipe. It turns out however that a basic cleaning is necessary, since in any old pipe deposits are always present which can fill a large portion of the flow cross section.
Since a bonding between the lining tube and the inner wall of the pipe can not occur with the fluid impermeable outer layer, unsealed locations, e.g. tears or damaged pipe joints, are not sealed so that water forced in from the earth collects in the annular space between the lining tube and the interior wall. Inspite of a new lining tube in the pipe ground water can filter in and the reverse can occur, i.e. waste water can seep out into the surrounding earth, at lateral inlets and service lines, which must be cut in a known way from the lining tube after installation. The lining tube can not be installed in the pipe by longitudinal sliding. Joining of the service lines can not be performed in the known process in such a way that the joints are water tight. There is a reverse flow which develops between the lining tube introduced and the pipe. Longitudinal shifting of the hardened tube can at least partially obstruct service lines and lateral openings.
The lining tube has an impermeable resin layer on its inner side.
Another method is known and described in German Patent 23 62 784, in which the lining tube fed into the pipe to be sanitized has a resin impermeable layer inside and a layer saturated with plastic resin outside. This lining tube is introduced by being turned inside out in the pipe so that it is put in the pipe with its plastic resin soaked layer facing exteriorly against the inside of the pipe. For the inversion of the two layer lining tube comparatively large forces are necessary because of the felting work in the inversion region. Because of this felting work resin is pressed out from the impregnated fiber layer and must be replaced by air.
In both known processes a lining tube is used, which has exclusively a fiber fleece layer soaked with hardenable plastic resin, so that a plastic resin type must be chosen. The current expensive polyester resin has the disadvantage that it forms no bond with the moist inner side of the pipe to be sanitized and during the hardening shrinks so strongly that a annular space forms between the pipe to be sanitized and the lining tube, which fills with water from the ground, which flows into the annular space through a break location in the old pipe and is forced in the sanitized pipe through service lines and lateral entrances. Also waste water can seep out into the surrounding ground by the same flow path.